Broadcast in point-to-point oriented packet-switched networks

ABSTRACT

The invention relates to a method, a broadcast management centre, a router, a host and a system for performing broadcast in a point-to-point oriented packet-switched telecommunication network. The basic idea is to use multicast for parts of the transmission within said telecommunication network. The multicast technique is used to send broadcast data to a geographical broadcast group to which a network node belongs. The network nodes are configured to a certain geographical broadcast group by the broadcast management centre.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a method, broadcast management centre,router, host and system for performing broadcast in a point-to-pointoriented packet-switched telecommunication network.

BACKGROUND

Broadcast allows the possibility of addressing a packet to alldestinations by using a special code in the address field. When a packetwith this code is transmitted, it is received and processed by everyuser on the network. Upon receiving a packet and if a user is notintended to receive the message, it discards the received packets. Incontrast to this the point-to-point communication means the sending of amessage from a single sender to a single receiver. Some broadcastsystems also supports transmission to a subset of the users, theso-called multicasting. Multicasting is a service that permits sourcesto send a single copy of the same data to an address that causes thedata to be delivered to multiple recipients, who are registered to amulticast group. Therefore multicasting is a form of broadcasting. Thedifference is that in case of broadcasting the user is not requested toregister to any group, the message is distributed to all users.

In broadcasting and also in multicasting only one copy of a messagepasses over any link in a network and copies of the message are madeonly where paths diverge. From the network perspective, broadcastdramatically reduces overall bandwidth consumption, since the data isreplicated in the network at appropriate points rather than in theend-systems. Further a server, which is sending broadcast messages,needs to manage only one session.

In the following the registration procedure of Internet Protocolmulticast will be handled in more details.

In case the multicast is used in Internet Protocol IP network then it iscalled IP multicast. Among other features characterising the IPmulticast, a specific form of addressing is applied using the existingIP address, like the so-called D-address in IP version 4.

Within the IP multicast the membership of a multicast session group isdynamic which means that hosts may join and leave groups at any time. Inorder to allow hosts on networks to indicate whether they wish to joinor leave a particular multicast group there is a protocol called theInternet Group Message Protocol IGMP. Thus this protocol lets the systemknow which hosts currently belong to which multicast group. Thisinformation is required by the multicast routers to know which multicastdata packet is to be forwarded onto which interface.

The IGMP is a part of the IP layer and the IGMP messages are transmittedin IP data packets. The version 1 of IGMP is described in RFC 1112 “Hostextensions for IP multicasting” S. E. Deering, Aug. 1, 1989, RFC 2236“Internet Group Management Protocol, Version 2” W. Fenner, November 1997describes the version 2. The IGMP has been developed for IP version 4.In Internet Protocol IP version 6 there is a similar protocol calledMulticast Listener Discovery MLD, which is used for the same purpose asthe IGMP. MLD provides more functionality as IGMP. The description ofthe first version of MLD can be found in RFC 2710 “Multicast ListenerDiscovery (MLD) for IPv6” S. Deering, W. Fenner, B. Haberman, October1999. However the messages used in MLD correspond to the IGMP messages.In the following the IGMP will be used as an example. Although thisshould not be restricted to the IGMP, the functionality of the inventionis also given by usage of MLD.

In principle the IGMP uses two basic messages to fulfil its tasks, themembership report and the membership query message and the followingrules are applied.

A multicast router sends a membership query at regular intervals to seeif any hosts still belong to any group. The router must send one queryout each interface. A host responds to a membership query by sending onemembership report for each group that still contains at least oneprocess. A host joins a group sending also the membership report.

Using the information received by applying the report and the querymessages a table with its interfaces having at least one host in amulticast group is established. After reception of the multicast data,the router forwards the data out on those interfaces, which have atleast one member.

With IP multicast receivers do not need to know who or where the sendersare to receive traffic from them and the senders never need to know whothe receivers are Neither senders nor receivers need to care about thenetwork topology as the network optimises delivery. The distribution ofthe information via the IP multicast is performed on the base of ahierarchical connection of the hosts, like for example a multicastdelivery tree. Several algorithms have been proposed for buildingmulticast distribution trees, like for example spanning trees,shared-trees, source-based trees, and core-based trees. The descriptionsof the corresponding algorithms can be found in “IP telephony:Packet-based multimedia communications systems” O. Hersent, D. Gurle, D.Petit, Addison-Wesley, Wesley, Harlow, 2000. After the establishment ofthe multicast delivery tree, the distribution of the information is doneby the IP multicast routing protocols. The detailed description of thecorresponding IP multicast routing protocols can be also found in theabove-mentioned document.

In order to explain the problem occurring by introduction of broadcastin a point-to-point oriented packet-switched telecommunication system inthe following an overview of the architecture of the General PacketRadio System GPRS network is given.

The GPRS is the packet-switched enhancement of the Global System forMobile Communication GSM, which is a circuit switched network. It meansthat the user can be permanently online connected but it has to pay onlyfor the real data transfer. In order to fulfil the new requirements somechanges are to be introduced into the GSM. Among other new logical nodesare to be introduced, the Serving GPRS Support Node SGSN and the GatewayGPRS Support Node GGSN. The main functions of the GGSN involveinteraction with external IP packet networks providing connections toInternet Service Providers ISPs via the Gi interface. The SGSN servesall GPRS subscribers that are physically located within the geographicalSGSN service area. It communicates via the Gn interface, which definesthe IP based backbone, with GGSN. The IP based backbone is therestriction of GPRS in that GGSN and SGSN are to be connected in a waythat IP is run on top of the technology chosen, meaning that SGSN andGGSN communicate via IP addresses. This restriction applies also for theIu-PS interface, which is defined between the SGSN and the Radio NetworkController RNC. The RNC manages Radio Access Bearers for user data, theradio network and mobility. The Radio Base Station called also BaseTransceiver Station BTS or simply Base Station BS or in 3GPP, Node B,provides the radio resources and communicates with the user equipmentover the Uu interface.

A detailed description of the architecture is to be found in 3GPP TS03.60 V7.5.0 (2001-01) 3^(rd) Generation Partnership Project; TechnicalSpecification Group Services and System Aspects, Digital cellularTelecommunications System (Phase 2+), General Packet Radio Service(GPRS), Service Description, Stage 2 (Release 1998).

Similar nodes and interfaces are also used in the next generation of thewireless networks, Universal Mobile Communication System UMTS asdescribed in 3GPP TS 23.060 V3.6.0 (2001-01) 3^(rd) GenerationPartnership Project; Technical Specification Group Services and SystemAspects, General Packet Radio Service (GPRS), Service Description, Stage2 (Release 1999).

In order to distinguish between the functionality of these nodes in UMTSextended names are often used, 3G-SGSN and 3G-GGSN. In the followingdescription it will not be distinguished between the GPRS and UMTSnodes.

Currently broadcast in mobile networks causes some problems. The impactson the problems have among other things the mobility of the end usersand low transmission bandwidth of the mobile network on the airinterface. Further the communication in a mobile communication networkslike for example in UMTS is a unicast communication. The unicastcommunication is also called point-to-point communication. In such kindof network, and in particular in the core network, it is not foreseen toperform broadcast or even multicast communication. The groupcommunication is implemented by means of a point-to-point communicationhaving a sender transmitting separately the same packets to eachreceiver, instead of one packet when broadcasting is used. This meansthe IP broadcast messages are sent from a router settled in an externalIP network, like the Internet to the mobile station via unicastconnection, because from the point view of the mobile station the routerin the Internet is the first node in which the IP connection terminatesand therefore the first node applicable for broadcast. Therefore thebroadcast is performed on the application IP layer and the network nodesbetween the server and the user forward merely the broadcast ormulticast messages within the core part of the network withoutdistinguishing between a broadcast message and a unicast message. Theexisting technology of a point-to-point oriented packet-switchedtelecommunication network, like UMTS does not foresee the utilisation ofefficient broadcast.

Beyond this, broadcast is fine when only several users share a smallLAN, but in bigger networks, like UMTS, in which a large number of usersare connected by different network nodes the broadcast becomes aproblem. In particular in mobile networks sending the broadcastinformation to all users leads to consume considerable amounts ofnetwork bandwidth. Further the user's equipment has to check thereceived information and in case of irrelevant information it has todiscard the received packets. This causes an inefficient utilisation ofthe network node's resources. However there are many applications, whichrelay on broadcast for example broadcasting service on demand, video andmusic programmes, multi-camera angle sport viewing and replay oralternate scenario dramas, which are programs, which continuationdepends on the result of voting of the receivers.

Often the applications using broadcast as a form of delivery depend onthe geographical location of the user. Not taking geographical locationinto account means that the broadcast messages are sent to all usersindependently from the matter whether this message could be interestingfor the user.

In general introducing and performing of broadcast in a protocol stack,which is basically point-to-point oriented causes problems, then in suchkind of networks a unicast channel is established for performingcommunication between two nodes.

SUMMARY AND DESCRIPTION OF THE INVENTION

It is an object of the present invention to provide a solution for anefficient introduction and performing of broadcast in a point-to-pointoriented packet-switched telecommunication network. In particular it isobject of the present invention to make the broadcasting depending onthe geographical user location.

The telecommunication network has a set of network nodes, wherein theset comprises a first router and at least one host serving at least oneuser. The first router can connect said telecommunication network with afurther network in case a broadcast capable server is located in thefurther network. It is also possible to have the broadcast capableserver located in the point-to-point oriented packet-switchedtelecommunication network. Said telecommunication network can of coursehave further network nodes, like for example further routers responsiblefor routing the data to the user. In one embodiment, a broadcastmanagement centre configures the network nodes for broadcastprovisioning within a geographical broadcast group. The broadcastcapable server sends the broadcast data to the first router. A multicasttechnique on the transport layer is used to route the broadcast datafrom the first router to the host belonging to the certain geographicalbroadcast group. The host uses broadcast techniques to send thebroadcast data to the at least one user.

The advantage of the multicast technique on the parts of thetransmission is a better utilization of the network resources. Thebroadcast data is not sent to every network node but only to the networknodes registered to the geographical group.

In a preferred embodiment of the invention the geographical broadcastgroup is defined as a geographical area, which is a part of a PublicLand Mobile Network PLMN. This can be for example a country likeNordrheinwestfalen or a city.

The configuration of the network nodes performed by the broadcastmanagement centre can be done directly. With this solution the networknodes belonging to the certain geographical area are addressed directly.This guarantees a fast configuration. However this implies that thebroadcast management centre has all required information about thenodes, which are to be configured.

In another embodiment of the invention the configuration performed bythe broadcast management centre is done indirectly such that a networknode is addressed to establish connection to the further network nodesbuilding the certain geographical area. The advantage is that thebroadcast management centre administrates information merely about somenetwork nodes and these nodes have information about further nodes. Byapplying this architecture the responsibility for configuration isdelegated to the network nodes.

In the embodiment, in which the configuration is done indirectly it isadvantageous to send a message to the network nodes, which are to beconfigured and the nodes register to the corresponding geographicalgroup. The registration can be done by means of existing techniques forregistration to a multicast group, like IGMP or MLD.

The configuration of the network nodes is done via an informationexchange interface between the broadcast management centre and thenetwork nodes. The configuration is merely a part of informationexchange done on said interface. Further information can be for examplethe requirements information regarding the Quality of Service QoS.

In a preferred embodiment of the invention it is foreseen to have aninformation exchange interface between broadcast capable server andbroadcast management centre in order to support the broadcast managementcentre with information, for example about the building of thegeographical broadcast group. For this purpose the server sendsinformation about a geographical area, which could be interested incertain broadcast application.

The multicast technique on the transport layer uses a transport levelmulticast group tunnel, which is established by means of transport layerprotocol for tunnelling. This means that for example in an IP switchednetwork, which has two IP layers, the application IP layer and thetransport IP layer as it is further described, the broadcast ormulticast transmission performed on the application IP layer is mappedto the transport IP layer. This means currently the broadcast ormulticast transmission is performed on the application IP layer. Theinvention proposes to redirect the broadcast or multicast transmissionfrom the application IP layer to the transport IP layer. This can bedone using a tunnel established on the transport IP layer for thecertain multicast group by means of a transport layer protocol fortunnelling, which preferably can be the GPRS Tunnelling Protocol GTP.

In a preferred embodiment data delivery in the multicast part of thetransmission is done using a multicast delivery tree, which can beestablished by means of existing multicast routing protocol.

It is advantageous to use the IP multicast, because of the existingdelivery techniques, like for example the IP routing protocols using theIP packet header, in which the identifier of the multicast group isincluded.

The transmission of the broadcast data from the host to the user is doneby means of a broadcast technique. In mobile networks this part of thetransmission represents a radio interface. In a preferred embodiment ofthe invention the broadcast technique on the radio interface can beimplemented by a broadcast bearer, delivering the same data to all usersin one cell.

It is advantageous that the network nodes perform the mapping of theparts of the transmission in order to deliver the broadcast data. Forexample the broadcast data delivered from the broadcast capable serveron a broadcast channel on the application IP layer are to be mapped inthe first router to multicast channels built on the transport layer.Further mapping is to be performed in a further router, which sends thereceived multicast data over a further multicast channel, which isidentified by another address. It can be also possible that a furtherrouter just forwards the received data. The mapping can results inadding or replacing the channels identifying addresses. It can alsoresult in packet encapsulation.

In one embodiment, a broadcast management centre for broadcast and/ormulticast management within a point-to-point oriented packet-switchedtelecommunication network is required for performing the invention. Saidnetwork is connected to a further network with a broadcast capableserver and has network nodes comprising at least one router and at leastone host serving at least one user. The broadcast management centre hasa configuration unit for configuration of the network nodes to ageographical broadcast group. This unit is responsible for defining thenetwork nodes and the required parameters in order to configure. Theconfiguration is submitted to the defined nodes by means of acommunication unit. The definition of the geographical broadcast groupis based on the information received by a receiving unit. Theinformation can be received from an operator or from the broadcastcapable server via an interface between the said server and thebroadcast management centre.

The invention presents also a router adapted to perform multicast in apoint-to-point oriented packet-switched telecommunication networkconnected to a further network with a broadcast capable server. The saidtelecommunication network has network nodes comprising at least one ofthe said router and at least one host serving at least one user. Therouter has a configuration unit for configuration of the network nodesin order to provide geographical broadcast group. The configuration canbe done either directly in the router or the configuration unit is alsorequested to configure further network nodes to a geographical broadcastgroup. The router has also a receiving unit for receiving data. The datacan be either multicast data received from a previous router orbroadcast data received from a broadcast capable server sitting on thefurther network. The received data is given to means for providingmulticast techniques on the transport layer in order to multicast thedata. A sending unit for sending the multicast data sends it towards thehost belonging to the certain geographical broadcast group. It means itcan be either a next router or a host.

In case the router has to adapt the received data for the furtherrouting according to a data structure for the administration of therelation between the received data and the sent multicast data is to beprovided.

Further the invention includes new functionality of a host. The host isto be adapted to perform broadcast in a point-to-point orientedpacket-switched telecommunication network wherein the host is connectedon one side to at least one router and on the other side to at least oneuser. The host has a receiving unit for receiving multicast data. Thisdata is sent from the router using a multicast technique on thetransport layer. After receiving the multicast data an association unitis used for establishment of association of the receiving data to thebroadcast data, which are sent to the user. The host provides means forproviding broadcast technique to the user. Depending on the interface tothe user different broadcast techniques can be used. The data is sent tothe user by means of a sending unit.

Further the invention discloses a system adapted to perform broadcast ina point-to-point oriented packet-switched telecommunication networkconnected to a further network with a broadcast capable server and saidtelecommunication network having network nodes comprising at least onerouter and at least one host serving at least one user. The systemincludes at least one router, at least one host, and a broadcastmanagement centre with the new functionality as described above.

In the following a detailed description of the invention is given.

FIG. 1: GPRS protocol architecture,

FIG. 2: Relation of the network nodes according to the invention,

FIG. 3: Configuration of the network nodes according to the invention,

FIG. 4: Registration procedure,

FIG. 5: Broadcast data delivery procedure.

In the following the realisation of the multicast in a point-to-pointoriented packet-switched telecommunication system is described.

The above-mentioned requirements and restriction for the functionalityand communication manner of the introduced packet switched orientednodes like SGSN or GGSN have their impact on the developed protocolstacks. As a result of the function of the GGSN as a router and as aninterface to the external networks the IP layer below the applicationlayer has been introduced. Further due to the restriction of having anIP network within the core network, it means between the GGSN and theSGSN and further to the RNC an IP layer has been introduced as atransport mean, below the application-specific tunnelling protocol.

The following description concentrates merely on the two IP layers inthe packet switched domain in respect to FIG. 1. FIG. 1 shows an user,MS, which is connected over the Uu interface with an access network,UTRAN. This network communicates via the Iu-PS interface with a 3G-SGSN.The 3G-SGSN communicates over the Gn interface with 3G-GGSN. The Giinterface defines the interface to a further network, like for exampleInternet.

In respect to FIG. 1 there are two IP layers, depicted as IP, PPP andUDP/IP, in the following described as application IP and transport IPlayer. The application IP layer is located directly below theapplication protocols, Applicat., in the protocol stack. The task ofthis IP layer is to connect the mobile station and the GGSN. This IPlayer is transparent to the core network like for example the packetswitching network. This is depicted in the FIG. 1 by a direct line goingfrom the MS to the 3G-GGSN. The second IP layer is the transport IPlayer used for transmission between the SGSN, GGSN and UTRAN. Thepayload traffic is transported across the Gn and Iu-PS encapsulated inan application-specific tunnelling protocol, the GPRS Tunnellingprotocol GTP-U, which is an example of a transport layer protocol fortunnelling. GTP packets use UDP as transport protocol. However there aredifferent tunnelling protocols, which are responsible for building atunnel and GTP is merely an example. In the FIG. 1 the other protocolsare mentioned due to the complementary reasons.

Regarding to the presented two IP layer architecture in the following apossible multicast technique on the transport layer is described.

The multicast technique uses a transport level multicast group tunnelTLMG, which is established by means of transport layer protocol fortunnelling like for example GTP Therefore in case of IP-multicast theidea is to map the multicast performed on the application IP layer tothe transport IP layer. On the transport IP layer a GTP tunnel isestablished for a multicast group. The tunnel is identified so that amapping between the arriving multicast data on the Gi interface to theGTP tunnel is guaranteed. The TLMG can be either established on demand,it means when the first multicast member registers to a multicast groupor it can be pre-established in order to make to initialisationprocedure faster. In the following a multicast member describes anetwork node, which is configured to be a member of a multicast group,which build a geographical broadcast group.

The establishment of a TLMG tunnel is done as following. At first theso-called PDP-Context activation is performed. The PDP contextactivation is like logging on the external IP network. For this aim amulticast member identity is associated with an IP address. During thePDP Context Activation a tunnel with an identity is created between themulticast member and the GGSN. During this procedure also Quality ofService QoS negotiation takes place. In order to register to a multicastgroup the multicast member sent an IGMP membership report message. Incase the multi-cast group as indicated in the IGMP Membership Reportdoes not exist in the GGSN yet, the GGSN creates a new entry for this.Additionally, the GGSN creates a Transport-Level-Multicast-Group TLMG onthe transport IP layer for the multicast arriving on the application IPlevel. For this purpose the GGSN allocates a multicast address from thecore network's address space. In the following it will be called theMulticast IP Address of the TLMG or alternative TLMG-MCAddress or simplyTLMG address. In order to create the proper TLMG, the GGSN can take thenegotiated Quality of Service QoS requirements from the PDP context intoaccount.

The GGSN informs the corresponding nodes that it has mobile stationsregistering for a multicast group by means of enhanced GTP protocol asan example. A new GTP message, SGSN Membership Report Request can beused. It is also possible to use existing message, for example anenhanced Packet Data Unit PDU notification message on the UDP connectionfor this purpose.

The SGSN Membership Report Request message contains information requiredfor the replication of the multicast stream into multiple unicaststreams in the certain node, like for example the TLMG-MCAddress and theidentification of the multicast member. Thus for the multicast grouptraffic the GGSN ignores the tunnel that is already established for thatMS by the SGSN during the PDP context activation and uses TLMGs, whichform a multicast delivery tree. This kind of multicast delivery treewill be called in the further description a TLMG delivery tree. Withthis method the to the GGSN over the Gi interface on the application IParriving multicast data are redirected from the application IP layer tothe transport IP layer, which performs the multicast in the core networkusing the TLMG delivery tree.

A deregistration from a multicast group is done by means of the IGMP andis requested by the broadcast management centre. For this purpose themulticast member sends an IGMP-Leave Message to the GGSN. The GGSN thencan send a new GTP message to the multicast member to request themembership release. This message carries as parameter the TLMG MCAddressand the address of the multicast member. Also the GGSN removes themobile station from the list for the corresponding multicast address orjust decreases the corresponding counter. In case this multicast memberwas the only one registered for the multicast group then the TLMG isreleased from the TLMG delivery tree.

The described TLMG technique is only an example for performing amulticast technique. In the following the performing of broadcast in apoint-to-point oriented packet-switched telecommunication network isdescribed in more details using any possible multicast technique in thecore network.

In the following the transmission of the broadcast or multicast dataperformed on the application IP layer will be called U-broadcast orU-multicast. In contrary to this the transmission on the transport IPlayer will be called T-broadcast or T-multicast. Further the broadcastor multicast service on the radio bearer will be called R-broadcast orR-multicast. Due to the fact that the broadcast or multicast on eachlayer provides a service in the following it will be also called U-, T-or R-multicast or broadcast service. For example a U-broadcast serviceis a broadcast application provided by the broadcast capable server, aT-multicast service can be any multicast technique on the transportlayer, which is provided by the network operator and a R-broadcast isany broadcast technique on the radio interface.

For the realisation of the invention additional new nodes or newfeatures in the existing nodes are to be introduced. In the followingthe new features of a router, on the example of the GGSN, new featuresof a host, on the example of RNC/Node-B, new features of the broadcastcapable router and broadcast management centre. In the following thebroadcast capable router will be called Multicast/Broadcast Server orMC/BC server and the broadcast management centre will be called MC/BCManagement Centre with the meaning that both nodes support alsomulticasting. The relation of the nodes is described in respect to FIG.2.

FIG. 2 shows the geographical broadcast network architecture. The basestations BS are connected to the RNC. A SGSN administrates via the Iu-PSinterface the RNCs and on the other side it is connected to the GGSN.The GGSN communicates via the Gi interface with a MC/BC Server. In FIG.2 this server is depicted as U-MC/BC Server. The U/T-MC/BC ManagementCentre via an interface going to the involved network nodesadministrates the whole architecture.

In the FIG. 2 this interface is depicted with the dotted line. They showthat an U/T-MC/BC Management Centre can address all nodes within anetwork for example in order to perform the configuration. For thepurpose of configuration messages in form of a request and of anacknowledgment message are exchanged between the U/T-MC/BC ManagementCentre and the corresponding nodes. In case there is a correspondinginterface a communication to a U-MC/BC server can be performed.

In the following the enhanced functionality of the GGSN is described.

In order to fulfil the new tasks the GGSN has to act as a localmulticast router, which is able to handle arriving IGMP messages.Usually the nodes register for specific multicast groups in the GGSN andthe GGSN keeps track of the active multicast groups in the packetswitched network.

Additionally, the GGSN creates multicast group in the scope of thenetwork, it means from the GGSN towards the BTS. This multicast groupcan be for example the above-described Transport Level Multicast GroupTLMG. The registration procedure is described further in more details.

Further the new functionality of a host is described. In case of UMTSthe task of a host can be performed by a RNC in connection with BTS orNode-B.

If the SGSN is ordered to T-multicast a service, the SGSN orders theRNCs to T-Multicast and the RNCs in turn order the BTS's or Node-B's toR-broadcast the service. Node-B stores the received multicast orbroadcast information and then either waits for the reception of theT-multicast data stream from the RNC or registers itself to thecorresponding T-multicast delivery tree. The RNC/Node-B maps theincoming T-Multicast service to a R-broadcast service.

In addition to a packet switched network and the nodes of the network,U-MC/BC servers, a corresponding U/T-MC/BC Management Centre, and anU/T-MC/BC Management Interface are needed.

In the following the U/T-MC/BC Management Centre is described.

The U/T MC/BC Management Centre is used to configure the T-multicast andR-broadcast services in the PLMN regarding to the requested U-service.The U/T MC/BC Management Centre may have an interface to the U-MC/BCServers in order to retrieve and send information about the U-MC/BCservice to be used for the T- and R-MC/BC service management andconfiguration in the PLMN. The information to be retrieved from theMC/BC server can be for example the multicast address of U-MC/BCservice, such that the GGSN can register itself to the correspondingmulticast group using this multicast address, and the required QoS forthe U-MC/BC service. Further the MC/BC server may send to the U/T MC/BCManagement Centre the specification of the geographical area for acertain U-BC Service.

The task of the U/T MC/BC Management Centre can be also fulfilled by anyother node, which has the above-mentioned functionality.

In the following the U-MC/BC server is described.

The U-MC/BC server contains and provides the U-broadcast service to thewireless subscribers in the PLMN. Said server is usually located in thefurther network, like for example the Internet und it does not have anyinformation about the structure of the connected networks. The U-MC/BCserver merely knows there is a network with at least one user, whichwants to receive the broadcast information. The transmission isperformed on the application IP layer, therefore the prefix U-. However,also a U-multicast service or a U-unicast service in the Internet can beused to provide a geographical U-broadcast service in the PLMN if theU-multicast/unicast service is handled in the GGSN like an U-broadcastservice. The difference is anyhow not visible to the end user within thePLMN.

Regarding to the introduced nomenclature and the introduced function ofthe existing or new nodes the basic idea of the present invention istherefore to introduce an efficient architectural solution for providingU-broadcast services to all subscribers that are able and willing toreceive the service in a specific geographical area of the PLMN. TheU-broadcast service provisioning involves a U-broadcast server, aT-multicast technique in the fixed infrastructure, which builds the corenetwork, and of a R-broadcast technique on the radio interface. TheU-broadcast service is support by a U/T-MC/BC management centre.

In the following a preferred embodiment of the invention is given. Itdescribes the configuration of the geographical areas.

Geographical U-broadcast services apply to the area covered by aBTS/Node-B, RNC, SGSN, GGSN or the whole PLMN it means consisting ofnodes in the distributing tree starting with the GGSN in the PLMN.Operators use the U/T-MC/BC Management Centre to configure one or morenodes in the PLMN for the U-broadcast service provisioning. Anotherpossibility for configuration is triggered by the MC/BC-server. It meansthe configuration is based on the parameters retrieved from theU-MC/BC-server. This solution is to be applied, when there is aninterface between the MC/BC-server and the U/T-MC/BC Management Centre.

The U/T-MC/BC Management Centre performs the configuration of a node inthe PLMN. This can be performed either directly or indirectly via any ofthe nodes higher up in the hierarchy. In the first alternative theU/T-MC/BC Management Centre orders a node to become part of a PLMNT-multicast group. It means the U/T-MC/BC Management Centre configuresthe BTS's and/or Node-B's directly to become part of the multicastgroup. This is done with registration done by means of an IGMP as it isdescribed below. The direct configuration of the BTS requires that thenodes higher up in the hierarchy get informed about the configuration inorder to deliver the broadcast data towards the BTS as it is describedin the broadcast data delivery procedure.

In the second solution the U/T-MC/BC Management Centre configures anintermediate node, like for example a SGSN and the SGSN is responsiblefor establishment of connection towards the BTS or B-Nodes. Theestablishment of connection can be based on a multicast delivery tree.For this purpose the nodes, which are to be connected, are requested toregister to the multicast group. The address of the multicast group issent with the request message. The for the connection establishmentaddressed node is also advised by the U/T-MC/BC Management Centre forthe size of the multicast group, this means for the nodes, which are tobe connected. For example the U/T-MC/BC Management Centre can configurean SGSN that should T-multicast a specific service in the whole coveragearea. The configuration can contain any description from a simpleconfiguration like the whole area up to more complex configurations likefor example the whole area except RNC-4.

Although it is possible to let the packet-switched network nodedetermine on its own the corresponding nodes from input such as areasbetween certain geographical coordinates, the logic to determine thenetwork nodes for the T-multicast should generally reside in theU/T-MC/BC Management Centre.

The multicast group registration of the nodes, which are addressed toconnect, is done by means of multicast group management mechanisms suchas IGMP or MLD as it is described below.

In the following the configuration procedure is presented in respect toFIG. 3.

The FIG. 3 includes the following nodes, the U/T-MC/BC Management Centredepicted as U/T-MC/BC Mgmt Centre, the U MC/BC Server, a gateway G, likefor example a GGSN, a serving node in between S, like for example anSGSN, an edge node R, like a BTS and a mobile station MT. Theconfiguration can be either started by 30 the operator 10, or in case aninterface to the MC/BC server exists by the said server, 10′. Theoperator has to make it manually in contrast to the configuration viathe interface to the MC/BC server, which makes it automatically. Withthis operation, the U/T-MC/BC Management Centre gets the informationabout the size of the multicast group with the belonging nodes. In thenext step, the U/T-MC/BC Management Centre can either make theconfiguration of the multicast group directly, 20 addressing the edgenodes 5 directly or indirectly via the nodes higher in the architecture,20′. In respect to FIG. 3, the U/T-MC/BC Management Centre sends amessage, 20′ to the gateway G. which takes care of establishment ofconnection, 30′ and 40′ towards the mobile station MT.

Of course more then one T-multicast group can exists in a network.

In the following a preferred embodiment of the invention is given. Itdescribes the registration procedure.

In case a BTS or Node-B is ordered to R-broadcast a T-Multicast servicein the corresponding geographical area, the BTS or Node-B receives theT-multicast address for the U-broadcast service and the required QoS.The U/T-MC/BC Management Centre can provide additional information inorder to be used for the registration to the T-multicast group. Due tothe fact that each node has information about all correspondinglower-level nodes in the hierarchy, instead of ordering each lower levelnode by means of a dedicated unicast message, a general configurationmulticast group can be used to address all lower level nodes. The BTS orNode-B stores the received multicast information and registers itself tothe corresponding T-multicast delivery tree. This can be done in case ofan IP transport network by means of IGMP/MLD and results in aT-multicast delivery tree with the BTS or Node-B as leaf of the tree.The registration message can be either send directly to the root of thetree or to the next nodes, which forwards the message towards the root.

In the following an embodiment of the registration procedure isdisclosed in respect to FIG. 4. The FIG. 4 shows an example forregistration, when a gateway is ordered 101 to establish connections tothe nodes belonging to the certain geographical area. For this purposethe gateway G sends a request message to the concerned nodes using thehierarchical principle 102, 103. In order to register to a multicastgroup the edge node, R sends an IGMP message to the gateway G 104 uponthe multicast delivery tree for T-multicast is established from thegateway to the edge nodes R, which are the leafs of the tree, 105, 106.The multicast delivery tree for T-Multicast can be for example based onthe above-described TLMGs. In this case after retrieving the IGMPmessage a TLMG is built from the GGSN, which is an example of a gatewayG towards the BTS, which are an example for edge node R. The GGSN canaddress the BTS directly or it can build a TLMG to the SGSN, which is anexample for serving node S, and instructs the SGSN to build up a TLMG tothe BTS. In fact a source based multicast tree is created between theGGSN and all affected nodes in order to provide T-multicast service. Itis also possible to have pre-configured TLMGs, which are pre-establishedwith a certain QoS parameters.

In the following a preferred embodiment of the invention is given. Itdescribes the broadcast delivery procedure in respect to FIG. 5. TheFIG. 5 includes same nodes as in to FIG. 3.

In the first step, the MC/BC server sends the broadcast data to thegateway G, 200. The broadcast data is sent via defined broadcastchannels. The gateway G is configured in the way that it knows 30 whichbroadcast channels corresponds to which T-multicast deliver tree withinthe network. For this purpose, the gateway G may administrate a mappingtable for mapping the broadcast channels existing on the interface tothe MC/BC server to the multicast channels in a multicast tree existingin the core network. The gateway G redirects the broadcast data from theuser layer, like for example the application IP layer, to the transportlayer, like for example the transport IP layer, which is used tomulticast the 5 data by means of a T-multicast deliver tree like theTLMG, 201, 202. The intermediate nodes, S after receiving theT-multicast data either simply forward it to the neighbouring nodes orfor additional processing for the data is made, like for example furthercapsulation. The data is sent by means of T-multicast 10 technique,until the edge node, R is reached. In generic description, in case ahigher-level node in the PLAN has to T-multicast a service in thecorresponding geographical area, the node orders all correspondinglower-level nodes to T-multicast the service. It means in case an SGSNis ordered to T-multicast a 15 service, the SGSN orders the RNCs toT-multicast. Preferably IP multicast is used to deliver the data to theedge nodes R. The edge node R makes a mapping from the T-multicast toR-broadcast and broadcasts the data to the users (MTs), 203.

Additional information can optionally be provided to the users in thecorresponding geographical area in order to inform these about theU-broadcast service and the corresponding contents. This U-broadcastservice information is kept in the U-MC/BC servers but might be updatedfrom the U/T-MC/BC management centre. It means the U-broadcast serviceinformation can be sent on a pre-configured default U-BC stream, whichis known by all terminals, like for example a videotext. Thedistribution of the U-broadcast service information can be also a taskof the U-MC/BC server, which informs the end user terminals about theavailability of a service. This might be achieved by sending informationabout the availability and the details of the retrieval of the programvia an available data transmission service, like for example SMS, USSD,WAP or a Session Announcement Protocol.

The information about the broadcast service availability is sentpreferably to those nodes, which belong to a certain geographical area.The configuration can be either performed, when the network is booted upand the broadcast service is adapted to the configuration or the networkis configured on demand, it means when a new broadcast service issupported a configuration of the network is performed. In the last caseit is preferably to use the interface between the broadcast capableserver and the broadcast management centre.

The solution covered in this invention focuses on the packet switcheddomain in GSM or UMTS network. In general, the idea can be appliedwhenever tunnelling is used, such as with GTP, L2TP, IPSec, Mobile IP,etc. Therefore the invention can be applied to any networks with two IPlayers, it means an application IP layer and a transport IP layer. Alsofor case where the transport layer is based on another technology thatsupports multicast transmission like for example ATM with multicastenhancements the mechanisms can be applied.

1. A method for broadcasting messages in a point-to-point orientedpacket-switched telecommunication network, said network having a set ofnetwork nodes comprising a first router and at least one host serving atleast one user, wherein the first router communicates with a broadcastcapable server that provides broadcast data, said method comprising thesteps of: receiving, at said broadcast management center, informationabout the building of a geographical broadcast group interested incertain broadcast data; configuring the network nodes by said broadcastmanagement centre for broadcast provisioning within said geographicalbroadcast group, said broadcast management centre ordering the networknodes to register to the geographical broadcast group; sending, fromsaid broadcast capable server, the broadcast data to the first router;using multicast techniques on the transport layer to route the broadcastdata from the first router to the at least one host belonging to thegeographical broadcast group; and using a broadcast technique to sendthe broadcast data from said host to the at least one user.
 2. Themethod according to claim 1, wherein the geographical broadcast group isdefined as a geographical area of a Public Land Mobile Network (PLMN).3. The method according to claim 1, wherein said step of configuringperformed by the broadcast management centre comprises the step ofdirectly addressing the network nodes belonging to the geographicalbroadcast group.
 4. The method according to claim 1, wherein said stepof configuring performed by the broadcast management centre is performedindirectly such that a network node is addressed to establish connectionto the further network nodes building the geographical broadcast group.5. The method according to claim 3, further comprising the step ofrequesting the network nodes to register to the geographical broadcastgroup.
 6. The method according claim 5 wherein the indication forregistration is performed by means of Internet Group Message Protocol(IGMP) or Multicast Listener Discovery (MLD) protocol.
 7. The methodaccording to claim 1, wherein said step of configuring comprises theexchange of information via an interface between the broadcastmanagement centre and the network nodes.
 8. The method according toclaim 1, wherein the broadcast capable server supports the broadcastmanagement centre by means of an information exchange interface betweenbroadcast capable server and the broadcast management centre.
 9. Themethod according to claim 1, wherein the multicast technique on thetransport layer uses a transport level multicast group tunnel, which isestablished by means of transport layer protocol for tunnelling.
 10. Themethod according to claim 9, wherein the transport layer protocol fortunnelling is a GPRS Tunneling Protocol (GTP).
 11. The method accordingto claim 1, wherein multicast data delivery is performed using amulticast delivery tree established by means of multicast routingprotocol.
 12. The method according to claim 1, wherein the multicast isan IP-multicast.
 13. The method according to claim 1, wherein thebroadcast technique comprises the broadcast technique provided on aradio interface with said at least one user.
 14. The method according toclaim 1, further comprising the step of mapping parts of thetransmission in the involved network nodes in order to deliver thebroadcast data to the at least one user.